HYDRAULICALLY-DRIVEN DEEP-WELL PUMPING UNIT Russian patent published in 1997 - IPC

FIELD: oil production. SUBSTANCE: unit contains hydraulic actuating and pneumatic balancing cylinders rigidly connected together; cylinders have pistons connected with rod of sucker-rod string. Pneumatic balancing cylinder is brought in communication with reversible chamber and with compressed air source; cavities of hydraulic actuating cylinder are connected with actuating pump and discharge line through inlet and outlet strings. Unit is provided with emergency protection device mounted in inlet passage of hydraulic actuating cylinder and made in form of hydraulic spool valve with two working chambers where rodless freely floating plungers are located; chambers of hydraulic spool valve above and under plungers are connected with chambers of hydraulic actuating cylinder through throttles and check valves above and under piston, respectively; they are provided with outlet passages connected with discharge line and shifted relative to each other. EFFECT: enhanced efficiency. 2 cl, 1 dwg